The present invention is generally directed to surgical instruments or tools. In particular, the present invention relates to electrosurgical instruments and systems having electrocautery energy supply conductors that provide inhibited current leakage and methods of performing a minimally invasive surgical procedure while preventing unintended capacitive coupling. The surgical instruments can advantageously be used in robotically controlled minimally invasive surgical operations.
Minimally invasive surgical techniques generally reduce the amount of extraneous tissue damage during surgical procedures, thereby reducing patient recovery time, discomfort, and deleterious side effects. One effect of minimally invasive surgery, for example, is reduced post-operative hospital recovery times. Because the average hospital stay for a standard surgery is typically significantly longer than the average stay for an analogous minimally invasive surgery, increased use of minimally invasive techniques could save millions of dollars in hospital costs each year. Patient recovery times, patient discomfort, surgical side effects, and time away from work can also be reduced by increasing the use of minimally invasive surgery.
In theory, a significant number of surgical procedures could potentially be performed by minimally invasive techniques to achieve the advantages just described. However, only a small percentage of procedures currently use minimally invasive techniques as certain instruments, systems, and methods are not currently available in a form for providing minimally invasive surgery.
Traditional forms of minimally invasive surgery typically include endoscopy, which is visual examination of a hollow space with a viewing instrument called an endoscope. One of the more common forms of endoscopy is laparoscopy, which is visual examination and/or treatment of the abdominal cavity. In traditional laparoscopic surgery a patient's abdominal cavity is insufflated with gas and cannula sleeves are passed through small incisions in the musculature of the patient's abdomen to provide entry ports through which laparoscopic surgical instruments can be passed in a sealed fashion. Such incisions are typically about ½ inch (about 12 mm) in length.
The laparoscopic surgical instruments generally include a laparoscope for viewing the surgical field and working tools defining end effectors. Typical surgical end effectors include clamps, graspers, scissors, staplers, and needle holders, for example. The working tools are similar to those used in conventional (open) surgery, except that the working end or end effector of each tool is separated from its handle by a long extension tube, typically of about 12 inches (about 300 mm) in length, for example, so as to permit the surgeon to introduce the end effector to the surgical site and to control movement of the end effector relative to the surgical site from outside a patient's body.
To perform a surgical procedure, a surgeon typically passes the working tools or instruments through the cannula sleeves to the internal surgical site and manipulates the instruments from outside the abdomen by sliding them in and out through the cannula sleeves, rotating them in the cannula sleeves, levering (i.e., pivoting) the instruments against the abdominal wall, and actuating the end effectors on distal ends of the instruments from outside the abdominal cavity. The instruments normally pivot around centers defined by the incisions which extend through the muscles of the abdominal wall. The surgeon typically monitors the procedure by means of a television monitor which displays an image of the surgical site captured by the laparoscopic camera. Typically, the laparoscopic camera is also introduced through the abdominal wall so as to capture the image of the surgical site. Similar endoscopic techniques are employed in, for example, arthroscopy, retroperitoneoscopy, pelviscopy, nephroscopy, cystoscopy, cisternoscopy, sinoscopy, hysteroscopy, urethroscopy, and the like.
Although traditional minimally invasive surgical instruments and techniques like those just described have proven highly effective, newer systems may provide even further advantages. For example, traditional minimally invasive surgical instruments often deny the surgeon the flexibility of tool placement found in open surgery. Difficulty is experienced in approaching the surgical site with the instruments through the small incisions. Additionally, the added length of typical endoscopic instruments often reduces the surgeon's ability to feel forces exerted by tissues and organs on the end effector. Furthermore, coordination of the movement of the end effector of the instrument as viewed in the image on the television monitor with actual end effector movement is particularly difficult, since the movement as perceived in the image normally does not correspond intuitively with the actual end effector movement. Accordingly, lack of intuitive response to surgical instrument movement input is often experienced. Such a lack of intuitiveness, dexterity, and sensitivity of endoscopic tools has been found to be an impediment in the increased use of minimally invasive surgery.
Minimally invasive robotic (or “telesurgical”) surgical systems have been developed to increase surgical dexterity as well as to permit a surgeon to operate on a patient in an intuitive manner. Telesurgery is a general term for surgical operations using systems where the surgeon uses some form of remote control, e.g., a servomechanism, or the like, to manipulate surgical instrument movements, rather than directly holding and moving the tools by hand. In such a telesurgery system, the surgeon is typically provided with an image of the surgical site on a visual display at a location remote from the patient. The surgeon can typically perform the surgical procedure at the location remote from the patient while viewing the end effector movement on the visual display during the surgical procedure. While typically viewing a three-dimensional image of the surgical site on the visual display, the surgeon performs the surgical procedures on the patient by manipulating master control devices at the remote location, which master control devices control motion of the remotely controlled instruments.
Typically, such a telesurgery system can be provided with at least two master control devices (one for each of the surgeon's hands), which are normally operatively associated with two robotic arms on each of which a surgical instrument is mounted. Operative communication between master control devices and associated robotic arm and instrument assemblies is typically achieved through a control system. The control system typically includes at least one processor which relays input commands from the master control devices to the associated robotic arm and instrument assemblies and from the arm and instrument assemblies to the associated master control devices in the case of, e.g., force feedback, or the like. An exemplary robotic surgical system is the DA VINCI™ system available from Intuitive Surgical, Inc. of Sunnyvale, Calif.
A typical electrosurgical treatment instrument is capable of treating tissue of an organism with the use of heat produced by electrical energy. The instrument typically includes an electrode or cautery hook that applies current to living tissue at a surgical site. Optionally, the instrument may comprise a combined cutting, shearing, clamping, stapling, or grasping electrosurgical instrument. As the tissue current is conducted through the tissue, the tissue temperature rises, ultimately causing desiccation, cutting, cauterization, and/or coagulation of the target tissue (i.e., blood vessels and the like). While such electrocautery instruments provide significant advances in minimally invasive surgical technology, some shortcomings still need to be addressed.
In particular, high voltage current may unintentionally leak from an electrocautery supply conductor that delivers electrical energy to an end effector (e.g., electrode) during a treatment procedure. This is especially a problem if fluids, such as blood or saline, enter or seep into an interior of an instrument shaft that houses the conductor due to shaft pressurization. Such seepage may cause increased capacitive coupling between the instrument shaft and a patient resulting in unintended current voltage being imparted to the patient. Conduction only at a tip of the end effector to the target tissue is desirable. Conduction by increased capacitive coupling is undesirable as it may cause unnecessary and unintended burning of the patient from the tool shaft. Furthermore, such increased capacitive coupling may be passed along the instrument and cause melting or burning of the surgical tool itself. Also, in the case of robotic surgical systems, which are of particular interest to the present invention, such increased capacitive coupling may be passed along the instrument to the telesurgical system in general causing damage to such a system, especially sensitive electronics. Another disadvantage is that high voltage current may unintentionally creep to an exterior surface of an exposed wrist-like mechanism which is provided between the end of the shaft and the end effector. In particular, fluid such as blood or saline may arc over the wrist surface from the conducting end effector tip and cause wrist surface conduction. Such wrist surface conduction in turn may also cause unintended burning of the patient and/or melting of the wrist mechanism.
Therefore, it would be desirable to provide improved electrosurgical instruments and systems having electrocautery energy supply conductors that provide inhibited current leakage and methods of performing a minimally invasive surgical procedure while preventing unintended capacitive coupling. It would be further desirable if such electrosurgical instruments, systems, and methods inhibit wrist surface conduction. The electrosurgical instruments should also be compatible with minimally invasive robotic surgical systems. At least some of these objectives will be met by the inventions described hereinafter.